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This study aimed to evaluate the capability of lactic acid bacteria (LAB) isolated from different kinds of fermented fish products (Plaa-som) on the production of γ-aminobutyric acid (GABA). Among them, isolate L10-11, identified as Lactobacillus plantarum, offered the highest GABA production and was selected for further study. The highest production of GABA was obtained within 48h from the de Man, Rogosa and Sharpe (MRS) medium, having a pH range of 5-6. Oncreasing the monosodium glutamate (MSG) concentration resulted in a higher accumulation of GABA and reached the highest concentration (15.74 g/L) using 4% (w/v) MSG, while high residual MSG was also observed in accordance with concentration increase. Dn the other hand, the addition of NaCl in the culture medium by up to 7% (w/v) did not suppress GABA production. Preliminary application of strain L10-11 as starter producing GABA was investigated in Thai fermented vegetables (Som-pak). Ot was found that GABA formation could be observed increasingly following the concentration of MSG added. GABA content in Som-pak was 5 times higher than that of control when inoculating Lb. plantarum L10-11 and adding MSG at 1% (w/v). On addition, sensory evaluation revealed that addition of this starter culture to Som-pak gave overall acceptability slightly higher than that which allowed fermentation to occur spontaneously. This alternative procedure would be successful for improving the nutritional quality of functional fermented food.

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Bacterial cellulose (BC) has attracted considerable scientific interest and can be modified, making it more widely useful in composites with guest nanoparticles. In this study, silica nanoparticles obtained from rice husks were used to prepare BC-silica composite aerogels (CAs) via a sol-gel method. Various amount of silica nanoparticles (3, 6, 9 and 12% w/v) dissolved in 2.5 M NaOH were used as a precursor for inclusion into BC. Subsequently, it was employed to form a SiO 2 gel skeleton in a BC matrix by adding 2 M H 2 SO 4, as a catalyst. Increasing levels of silica nanoparticles led progressively lower transmittance values of BC-silica CAs. SEM images revealed a surface morphology of spheroid particles with little agglomeration. The XRD diffraction peaks were gradually covered by a broad peak of silica as increasing silica content. Similarly, FTIR spectroscopy results also indicate the presence of silica in proportion to its content. Furthermore, addition of silica nanoparticles improved the thermal properties using TGA analysis, shifting the decomposition temperature of BC up to 550°C and retaining of BC weight at least 60% with the BC sample with 3% of silica. This unique characteristic implies that silica had a stabilizing effect on polymeric cellulose. These results demonstrate an economical and environmentally friendly preparation of BC-silica CAs that can benefit material applications.

SummaryThe standardized karyotype and idiogram of the sand goby (Oxyeleotris marmoratus) from Chi River in the Maha Sarakham Province of northeastern Thailand were studied. Kidney cell samples were taken from five male and five female fish. The mitotic chromosome preparations were prepared by blood cell culture and directly from kidney cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of O. marmoratus was 2n = 46 and the fundamental number (NF) as 50 in both males and females. The types of chromosomes were 2 large submetacentric, 10 large telocentric, 2 medium metacentric and 32 medium telocentric chromosomes. No strange-sized chromosomes related to sex were observed. The region adjacent to the telomere of chromosome pair 7 showed clearly observable secondary constriction/NORs. The karyotype formula for O. marmoratus could be inferred as: 2n (diploid) 46 = L 2 sm +L t 10 +M 2 m +M t 32

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Acetic acid bacteria (AAB) isolated from natural resources and fermented plant beverages were screened to produce 1,